$A$ loop of irregular shape of conducting wire (as shown in the figure) is placed in a uniform magnetic field perpendicular to the plane of the paper. If the loop changes into a circular shape,the direction of the induced current will be:

There are two square loops $A$ and $B$. When $A$ moves towards $B$,a current starts flowing in $B$ as shown in the figure,and the current in $B$ stops when $A$ stops moving. From this,we can infer that (Assume loop $B$ is at rest):

Magnetic flux passing through a coil is initially $4 \times 10^{-4} \ Wb$. It reduces to $10 \%$ of its original value in $t$ seconds. If the induced emf is $0.72 \ mV$,then $t$ in seconds is:

$A$ coil having $200$ turns has a surface area of $0.15 \ m^2$. $A$ magnetic field of strength $0.2 \ T$ applied perpendicular to this changes to $0.6 \ T$ in $0.4 \ s$,then the induced emf in the coil is . . . . . . $V$.

The magnetic flux through a coil perpendicular to its plane and directed into the paper is varying according to the relation $\phi = (2t^2 + 4t + 6) \, mWb$. The $emf$ induced in the loop at $t = 4 \, s$ is ....... $V$.

$A$ hundred turns of insulated copper wire are wrapped around an iron cylinder of area $1 \times 10^{-3} \ m^2$ and are connected to a resistor. The total resistance in the circuit is $10 \ \Omega$. If the longitudinal magnetic induction in the iron changes from $1 \ Wb/m^2$ in one direction to $1 \ Wb/m^2$ in the opposite direction,how much charge flows through the circuit?